Noise reducing apparatus for a vibrating screen sifting machine

ABSTRACT

Noise reducing apparatus for a vibrating screen sifting machine including a jacket made of lead-impregnated plastic and expanded cellular material for the housing of the vibrating mechanism, a mastic material coating on the outer surface of the screen frame, and rubber inserts between various of the metal components.

United States Patent Harkness Sept. 17, 1974 NOISE REDUCING APPARATUS FOR A 3,741,335 6/1973 Lebeau 181/33 K VIBRATING SCREEN SIFTING MACHINE 3,773,140 11/1973 Mahajan et a1. 181/33 K [75] Inventor: Richard Ernest Harkness, Hudson, FOREIGN PATENTS OR APPLICATIONS OhlO 824,247 11/1937 France 181/33 K [73] Assignee: Combustion Engineering, Inc.,

Windsor, Conn. Primary Examiner-Richard B. Wilkinson Assistant Examiner.lohn F. Gonzales [22] Flled' 1973 Attorney, Agent, or Firm-Robert L. Olson [21] Appl. No.: 415,696

[57] ABSTRACT g 181/33 Noise reducingapparatus for a vibrating screen sifting [58 d 368 370. machine including a jacket made of lead-impregnated 1 0 earc 18033 plastic and expanded cellular material for the housing of the vibrating mechanism, a mastic material coating [56] R f Ct d on the outer surface of the screen frame, and rubber UNITE; g r z lf gs I ZTENTS inserts between various of the metal components. 3,625,355 12/1971 Schurrer 209/21 5 Claims 4 Drawing Figures 3e 32 /V X V i 29' 43 40 s 20 ,//0

EAn-jmwszr 1 1 1924- v SHEET 1 or 3 NOISE REDUCING APPARATUS FOR A VIBRATING SCREEN SIFTING MACHINE BACKGROUND OF THE INVENTION A common type of separating apparatus is a screen sifter, using a continuous operating vibrating mechanism for keeping the screen from becoming plugged. This is a rather noisy piece of equipment, and in view of the recent concern about noise pollution, most industries are taking steps to reduce noise levels in all areas where personnel are working.

SUMMARY OF THE INVENTION The vibrating screen sifting machine of the invention is provided with noise reducing apparatus including a jacket made of lead-impregnated plastic and expanded cellular material, elastic inserts between various of the metal components, and a mastic material coating on the outer surface of the screen frame.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional side view of a vibrating screen sifting machine having noise reducing means attached thereto;

FIG. 2 is a perspective exploded view of the vibrating mechanism with the insulating jacket not shown;

FIG. 3 is a perspective of the sifting machine; and

FIG. 4 is another perspective of the sifting machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, denotes a vibrating screen sifting machine having a rectangular screen frame 12 within which is secured a screen 14. The screen is subjected to continuous vibration by the electric vibrating mechanism 16. Vibrator 16 consists of a coil and magnet 18, and an armature 20. Adjustable spring 22 biases the armature away from the coil and magnet assembly. An interrupted DC current output of 1800 cycles per minute is supplied to the vibrating mechanism 16, thereby causing rapid vibration. The vibrations are transmitted to the screen 14 by means of a post 24 secured at its upper end to the armature 20, and at its lower end to the screen 14. Metal strips 26 and 28, which run the entire length of the screen 14, are positioned above and beneath the screen, respectively, so that the entire screen vibrates. The screen frame 12 is supported by beams 30, and the housing 32 for the vibrating mechanism 16 is supported by means of a pair of mounting brackets 34.

The manner in which the sifter 10 operates is fairly simple. Material is fed into frame 12 above the screen- 14 from one end, and removed from the other end. The frame 12 is at an angle to the horizontal, so as to cause the material to progress through the machine. Undersized material falls through the screen, and is removed either manually or by an automatic conveying mechanism, depending on what material is being separated. Vibrating the screen greatly increases the separating capacity, and also prevents the screen openings from becoming plugged. The only disadvantageous feature of the vibrating mechanism is the noise that accompanies its operation. In order to reduce the noise emanating from the machine, noise reducing apparatus has been added. Looking again to FIG. 1, a jacket 36 encloses the vibrator mechanism housing 32 and the mounting brackets 34. The jacket 36 is comprised of an outer flexible plastic layer impregnated with lead, and an inner expanded cellular material layer, for example of styrofoam. The lead will absorb the low frequency sound vibrations and the cellular material will absorb the high frequency sound vibrations. Glued to the inner walls of housing 32 are pieces of styrofoam 38 as best seen in FIG. 2. The two large cavities of housing 32 are filled with blocks 40 of styrofoam, which can also be glued in place.

Looking again to FIG. 2, rubber isolators 42 are used on the nut and bolt connections between the mounting brackets 34 and the vibration mechanism housing 32. These isolators prevent metal to metal contact, thus reducing the vibrations transmitted between these parts. Isolators 46 are located at the connection between frame 12 and the support beams 30. Strips of rubber 48 are used along the straps securing the screen 14 to the frame 12. Isola'tors 50 are used on the bolts securing these straps.

The outer walls of frame 12 are coated with a layer of mastic material 52 (FIGS. 3 and 4) to deaden the vibration capabilities of frame 12. The dust covers 54 (FIG. 1) have rubber strips 56 glued along the edges which rest on the upper surface of frame 12. With all of the above noise reducing features added to the vibrating screen sifting machine, it is possible to reduce the noise level to a point where personnel can comfortably work in the area:

What is claimed is:

1. Noise reduction apparatus for reducing the noise emanating from a screen sifting device, the screen sifting device including a horizontal rectangular frame being open on top and bottom, a screen member secured inside the frame, first vertical support members beneath the frame for supporting the frame, second vertical support members secured to and extending above the frame, a housing connected to and supported by the second support members, vibrating means positioned within the housing, post means connecting the vibratory means to the screen member so as to transmit vibrations to the screen member, and jacket means enclosing the housing and second support members, said jacket means having an outer flexible plastic layer impregnated with lead, and an inner expanded cellular material layer, such that the lead will absorb the low frequency sound vibrations and the cellular material will absorb the high frequency sound vibrations.

2. The combination set forth in claim 1, including expanded cellular material secured to the inner surface of the housing.

3. The combination set forth in claim 2, wherein the first and second support members, the frame, and the housing are all made of metal, and elastic material is placed between each of the above, such that there is no metal-to-metal contact therebetween.

4. The combination set forth in claim 2, wherein a layer of expanded cellular material is attached to the inner surface of the housing.

5. The combination set forth in claim 4, wherein the outer surface of the frame has a layer of mastic material thereon. 

1. Noise reduction apparatus for reducing the noise emanating from a screen sifting device, the screen sifting device including a horizontal rectangular frame being open on top and bottom, a screen member secured inside the frame, first vertical support members beneath the frame for supporting the frame, second vertical support members secured to and extending above the frame, a housing connected to and supported by the second support members, vibrating means positioned within the housing, post means connecting the vibratory means to the screen member so as to transmit vibrations to the screen member, and jacket means enclosing the housing and second support members, said jacket means having an outer flexible plastic layer impregnated with lead, and an inner expanded cellular material layer, such that the lead will absorb the low frequency sound vibrations and the cellular material will absorb the high frequency sound vibrations.
 2. The combination set forth in claim 1, including expanded cellular material secured to the inner surface of the housing.
 3. The combination set forth in claim 2, wherein the first and second support members, the frame, and the housing are all made of metal, and elastic material is placed between each of the above, such that there is no metal-to-metal contact therebetween.
 4. The combination set forth in claim 2, wherein a layer of expanded cellular material is attached to the inner surface of the housing.
 5. The combination set forth in claim 4, wherein the outer surface of the frame has a layer of mastic material thereon. 